We are two weeks into growth and our stems on the hydroponic sprouts are starting to turn brown and collapse. They are not dry, but seem to be withering or rotting. They are being grown under a grow lamp, and the soil group next to them are doing fine....water has been changed once. Any suggestions?

Thanks

Additional information about their experiment so far:

Also, to confirm, you are using the grow lamp for both the hydroponicplants and the soil plants, right? And the same amount of time for

we are using the 15W T-8 fluorescent grow lamp on a timer for 12hrs of light per day for soil and hydroponiceach. Lamp is placed about 15 inches above top of pots.

Both of your samples are using lettuce seeds from the same packet, correct?

we used the seeds from the kit for both

Also, following the directions in the project, you are aerating thenutrient solution twice a day? (Step 6 of "Growing and FeedingInstructions": make sure to aerate the nutrient solution in theterrarium. A plant's roots need oxygen in order to grow. Follow theinstructions to learn how to use the manual hydro-pump to do this. Youshould aerate the solution twice a day.)

Yes we are aerating twice/day

In addition, the nutrientsolution should be replaced each week -- and strengthened once theroots appear: "Replace the nutrient solution in the hydroponicsterrarium every week. Once you can see the roots stick out from therock wool, strengthen the nutrient solution as directed in theinstructions.")

we have only changed the nutrient solution once after its initial fabrication.

I am not an expert on plants, but I have a couple suggestions for you. First, it may be that you need to strengthen your nutrient solution more.

In addition, the nutrient solution should be replaced each week -- and strengthened once the roots appear: "Replace the nutrient solution in the hydroponics terrarium every week. Once you can see the roots stick out from the rock wool, strengthen the nutrient solution as directed in the instructions.")

we have only changed the nutrient solution once after its initial fabrication.

My second idea is that some sort of microorganism (bacteria or fungus) contaminated your hydroponic setup but not the soil. The way the water circulates among all the plants in the hydroponic setup, it would make sense that a single infection would affect all the plants similarly.

Since you are only a couple weeks into your experiment, is there an option for you to try again?

Whether you are able to start over or not, it would be good to make as many observations as you can. Sometimes experiments do not work as expected, but you can still learn something from them! Even lysozyme (now a widely used enzyme in research) was discovered by accident - when the researcher sneezed on his bacterial plates and inadvertently killed some of the bacteria with the lysozyme in his saliva! So try making as many detailed observations as you can about the condition of your plants, and see if you can do some online research to identify what might be plaguing your hydroponic plants. Discovering what went wrong is still an experiment of sorts!

[Science Buddies note: This student has started over, replanting seeds (of a different variety this time). Once again, they are seeing less than satisfactory growth results from the hydroponics seedlings). Can anyone offer additional input? Their other plants, in soil, are continuing to grow well.]